Posted: Thursday, January 06, 2011 11:00 AM
Growers extend growing season with plastic hoop houses
Farmers in the U.S. are relying more on greenhouses and protective covers to shield their food crops from the weather, according to new USDA data.
In the past decade, the value of fruits and vegetables grown under cover has more than doubled, as has the square footage of such operations.
Though the total amount of food produced in this way amounts to a "drop in the ocean," it's still a financially useful tool for growers, said Nick Andrews, small farms extension agent at Oregon State University.
"They can capture a lot more income by extending their season," he said. "For the farmers doing it, it can be an important income source."
In California, the top state where food is grown under cover, blackberry and raspberry producers are the primary users of the technique, said Timothy Hartz, an extension specialist and agronomist with the University of California.
For the most part, farmers are using plastic hoop houses rather than actual climate-controlled greenhouses, he said. Even then, materials and labor are more expensive than with conventional production.
The method nonetheless pencils out for many farmers due to advantages in yield and quality, Hartz said.
By filtering out sunlight, especially with whitewash or shade cloth, growers can avoid sun scald on fruit. Excluding rain minimizes the risk of fruit rot, and wind protection prevents scarring.
"You take these benefits together and they justify the relatively high cost of those tunnels themselves," Hartz said.
Using protective covers isn't feasible in all situations, he said. Farmers must tailor each system to meet their individual needs.
Production of other crops, such as tomatoes and peppers, also occurs in California hoop houses, but it's more common among smaller farmers who rely on direct marketing, he said.
Due to the additional costs involved, protective covers make more sense for farmers who can obtain higher prices for their crops, said Bob McReynolds, an extension agent for vegetable production at Oregon State University.
Larger farmers who sell on the wholesale market in Oregon may put some squash and cucumbers under row covers, but it's not very common, McReynolds said.
"It's still pretty cost prohibitive," he said. "The wholesale growers I work with, I'm not seeing any expansion."
Direct market customers such as chefs and restaurants are often interested in unique varieties of local produce that may not typically be available in the region or during certain seasons -- creating a niche for small farmers to fill, Andrews said.
"For most farms, the greenhouse is a relatively minor part of their business, but it's a good diversification and gives them some insurance against the weather and access to the early, high-value markets," he said.